Lifting jack



Dec. 2, 1969 J. N. SUNSERI LIFTING JACK Filed Aug. 24, 1967 2Sheets-Sheet 1 ATTORNEYS Dec. 2, 1969 Filed Aug. 24,

J.- N. SUNSER! 3,481,581

LIFTING JACK 2 Sheets-Sheet 2 IN VENTOR. JOE N. SUNSERI ATTORNEYS UnitedStates Patent Oifice 3,481,581 Patented Dec. 2, 1969 3,481,581 LIFTINGJACK Joe N. Sunseri, 745 E. Hedding St., San Jose, Calif. 95112 FiledAug. 24, 1967, Ser. No. 662,956 Int. Cl. B66f N04 US. Cl. 254-408 12Claims ABSTRACT OF THE DISCLOSURE An improved lifting jack of the typehaving a horizontal rack and a carriage mounted on the rack for movementincrementally along the same wherein a lever arm, whose lower end isconnected to the carriage and whose upper end has weight-supportingmeans thereon, will be moved in a direction to elevate theweight-supporting means as the carriage moves forwardly toward one endof the rack. The lower end of the lever arm is coupled to the rear endof the carriage with reference to the direction of forward movement ofthe carriage. Means coupled with the lower end of the lever arm and thecarriage engages the underside of the rack as the carriage moves alongthe same.

This invention relates to improvements in lifting jacks and, moreparticularly, to a jack of the type having a horizontal rack andgenerally known as a low-profile jack.

The present invention is directed to a lifting jack of the typedescribed wherein certain components of the jack are arranged relativeto each other to provide greater efiiciency in lifting a given weightand to provide a longer operating life for the jack. The structure ofthis type of jack includes a rack adapted to be disposed in a horizontalposition, a carriage mounted on the jack for reciprocation and havingdog or pawl means engageable with the teeth of the rack forincrementally moving the carriage along the rack, and a pair of leverarms pivotally connected to the rack and the carriage respectively, tocause weight supporting means on the upper end of one of the lever armsto be raised to elevate a load as the carriage moves toward one end ofthe rack.

Specifically, the invention centers around the location at which the onelever arm is connected at its lower end to the carriage, and the use ofbearing structure to transfer a part of the load to the rack rather thanhave the carriage sustain all of the load as in prior structures, Thisconnection is made at the bottom of the carriage and at its rear endwith reference to its forward direction of movement so that the bearingstructure can be coupled to the lower end of the lever for shiftableengagement with the underside of the rack.

Lifting jacks of the type having horizontally disposed racks have beenused in the past, but the lever arm having the weight-supporting meansthereon has always been attached to the carriage at the forward endthereof with reference to its direction of movement for elevating theweight-supporting means. Since the pawl or dog structure on the carriageeffectively applies a force to the carriage generally to the rear of theconnection of the lever arm to the carriage, the lever arm is, ineffect, pushed upwardly by the carriage as the latter moves forwardlyalong the rack.

Several problems encountered with prior jacks of this type includeburring of the teeth on the rack and the relatively high input forcewhich must be manually applied to cause the carriage to raise the weightsupporting means. When the teeth of the rack become burred, the jackitself becomes inefficient due to the slipping of the pawls on the=burred teeth. The burring of the teeth results from excessive forceapplied thereto by the pawls since considerable force is required to pusthe lever arm upwardly. This applied force must be also exerted on theteeth since the teeth form the fulcrum for the pawl structure. Unlessthe material forming the teeth is of high quality and strength, the rackbecomes completely ineffective after only a relatively few uses.

An extremely important feature of this invention is the way in whichpressure on the teeth of the rack is minimized so as to prevent theteeth from becoming burred. This is accomplished by having the rackitself absorb some the load applied by the lever arm due to the weightat its upper end. To provide for this, hearing structure, such as aroller, is attached to the lower end of the lever arm and shiftablyengages the underside of the rack for movement along the same with thecarriage.

, Since the lower end of the lever arm tends to rotate upwardly due tothe weight applied at its upper end, this rotational tendency iseffectively countered by the rack which absorbs a part of the load sothat the carriage will not be subjected to the entire load. As a result,less force is exerted on the teeth of the rack by the pawl structure onthe carriage. Thus, the teeth are not damaged, i.e., burred, byexcessive force and the operating life of the jack is thereby extended.

The amount of manually applied force required to move the carriage ofprior lifting jacks is also a factor. With the lever arm mounted on theforward end of the carriage, as is the practice in the prior jacks, thecarriage must exert a push on the lever arm in order to elevate a weighton its upper end. As compared with a pull on the lever arm, a pushrequires more effort to lift a given weight. This is analogous to anindividual trying to advance a vehicle, such as an automobile, in aforward direction. By pushing on the rear of the vehicle, more effort isrequired than if the individual were to pull the front of the vehicleforwardly applying the analogy to a lifting jack of this type, thepulling force exerted on the lever arm by the carriage requires lesseffort than is required to cause the carriage to push the lever arm. Thepresent invention provides for a pull by the carriage on the lever armby connecting the lower end of the lever arm to the rear end of thecarriage. Thus, amount of force applied to the carriage to advance italong the rack will be less than that required to advance it when thelever arm is connected to the front end of the carriage.

The lifting jack of this invention has a variety of uses and isespecially adapted for use with passenger automobiles wherein the jackmay be conveniently stored in a collapsed condition in the trunk area.The invention is also adapted for application to existing bumper jacksby modifying the same to attach the two lever arms to the rack andcarriage respectively. To accomplish this, a pair of supports areconnected to the ends of the rack to allow the rack to be disposed in ahorizontal position spaced above a supporting surface. The two leverarms can then be pivotally connected to the rack and the carriagerespectively, with the one arm being attached to the rear of thecarriage and the other arm being connected to the front end of the rack.The carriage will be provided with a projection to allow the lever armto be connected to the carriage near the underside of the rack, wherebythe roller can be disposed adjacent to and in engagement with theunderside of the rack.

It is the primary object, therefore, to provide improvements in liftingjacks of the type utilizing a horizontal rack wherein the location atwhich the lever arm having the weight-supporting means thereon isconnected to the carriage allows the jack to be used over extendedperiods of time without damaging the teeth of the rack or the pawlstructure of the carriage and permits the force required to advance thecarriage along the rack to be reduced over that required to move thecarriage on conventional lifting jacks of this type.

Another object of this invention is to provide a lifting jack of thetype described wherein one of the pair of lever arms required for suchjack is coupled to the normally rearmost end of the carriage so that thecarriage will apply a pull to the lever arm as a weight is beingelevated rather than a push as has been heretofore relied upon inconventional lifting jacks of this type.

A further object of this invention is to provide an improved liftingjack of the type described wherein the lever arm connected to the rearend of the carriage has a laterally extending roller thereon whichengages the underside of the rack so that the rack acts to absorb a partof the load exerted by the lever arm to thereby minimize the forceexerted on the carriage and thereby the pressure exerted on the teeth ofthe rack by the pawl structure of the carriage.

Still another object of this invention is to provide a lifting jack ofthe horizontal type which can be made from a conventional bumper jack bythe attachment to such jack of the two lever arms and pivot means forconnecting one arm to the rear arm of the carriage and the other arm tothe forward end of the rack with a minimum of modification to the bumperjack itself.

Other objects, features and advantages of the present invention will bemore apparent after referring to the following specification andaccompanying drawings in which:

FIG. 1 is a top plan view of the lifting jack embodying the teachings ofthe present invention;

FIG. 2 is a side elevational view of the jack;

FIG. 3 is a cross-sectional view taken along line 3-3 in FIG. 2;

FIG. 4 is an enlarged, fragmentary, cross-sectional view of the jack,illustrating the interior of the carriage and the way in which thelifting lever arm is coupled thereto; and

FIG. 5 is a schematic view of a portion of the jack illustrating the wayin which forces are applied to the carriage and to the lifting leverarm.

The lifting jack of this invention is broadly denoted by the numeral andincludes a rack 12 adapted to be disposed in a horizontal position, acarriage 14 mounted on rack 12 for movement in opposed directions alongthe same and a pair of lever arms 16 and 18 pivotally connected at theirlower ends to the rack and the carriage respectively as shown in FIG. 2.Arm 18 has a foot or pad 20 on one end thereof for engaging theunderside of an object to be elevated, such as the frame of a vehicle.Pad 20 moves up and down in response to the movement of carriage 14 backand forth along rack 12.

Rack 12 is provided with a plurality of longitudinally spaced teeth 22on the upper extremity thereof. The rack may have any desiredcross-section but, for purposes of illustration, it has thecross-section shown in FIG. 3 wherein it is provided with side surface24 for supporting inwardly extending portions 26 on carriage 14. Rack 12is also provided with a pair of fiat surfaces 28 on the undersidethereof for a purpose to be described. A pair of feet 30 are secured tothe rack at opposite ends thereof for supporting the same in a generallyhorizontal position spaced above a supporting surface.

Carriage 14 provides a tubular housing for a pair of pawls or dogs 32and 34. A jacking lever 36 is pivotally coupled to the carriage by a pin38 and extends upwardly and outwardly therefrom, dog 34 being pivotallycoupled to the carriage on pin 38 and dog 32 being pivotally coupled tojacking lever 36 by a pin 40 spaced from pin 38 as shown in FIG. 4. Aspring 42 interconnects dogs 32 and 34 and a lateral projection 44 on arotatable arm 46 moves into and out of biasing relationship to spring42. When projection 44 biases the spring downwardly, the spring forcesdogs 32 and 34 towards teeth 22. The dogs are then in positions to causecarriage 14 to move forwardly as jacking lever 36 is moved up and down.When projection 44 is out of biasing relationship to spring 42, there isno tendency to force the dogs toward the teeth. The dogs are then inposition to cause the carriage to move in reverse as jacking lever 36 ismoved up and down. Carriage 12, including dogs 32 and 34, lever 36,spring 42 and projection 44, is essentially of conventional constructionand is the structure normally used with bumper jacks.

Arm 16 is comprised of two sections on opposed sides of the rack, eachsection being pivotally coupled to the forward end 48 of rack 12 by apin 50 which extends transversely to the rack adjacent to the lowersurfaces 28 thereof as shown in FIG. 2. The opposite end of each sectionof arm 16 is coupled by a pin 52 to a corresponding section of arm 18between the ends of the latter and adjacent to the end having pad 20thereon, arm 18 also having a pair of sections 58 on opposed sides ofthe rack. It is to be noted that pad 20 is pivotally coupled by a pin 54to the upper end of arm 18.

Carriage 14 is provided with a pair of projections 56 (FIGS. 2, 3 and 4)which extend downwardly from its normally bottommost margin on opposedsides of the rack. Sections 58 of arm 18 are connected at their lowerends by a pin or shaft 60 to respective projections 56 in the mannershown in FIG. 3. A roller 62 is rotatably carried on shaft 60 andnormally engages the fiat surfaces 28 on the underside of rack 12. Thus,roller 62 is in rolling engagement with the underside of the rack andthe rack is in load bearing relationship to lever arm 18.

In operation, jack 10 is disposed on the ground in a collapsed positionwith the rack substantially horizontal and with carriage 14 adjacent tothe opposite end 64 of rack 12 opposite to end 48. Thus, pad 20 will bespaced below the object to be elevated. A bar 66, such as lug wrench, isinserted into the tubular outer end 68 of jacking lever 36 in the mannershown in FIG. 2 and arm 46 is rotated in a direction to cause projection44 to bias spring 42 inwardly.

By applying an up-and-down movement to bar 66, dog 32 is caused to bereceived within the spaces between successive teeth, whereupon the dog32 acts as a fulcrum as force is applied to the carriage to cause it tomove toward end 48 of rack 12. Dog 34 prevents reverse movement of thecarriage as dog 32 is progressively advanced to the spaces betweenadjacent teeth.

As carriage 14 is advanced toward end 48, pad 20, after engaging theobject to be elevated, is moved upwardly inasmuch as lever arm 18becomes more and more vertical due to its connection with carriage 14and lever arm 16. As the desired elevation is attained, the jackingaction is halted whereupon the necessary operations can be performed onthe elevated object.

When it is desired to lower pad 20, projection 44 is swung away fromspring 42 and pawls 32 and 34 allow carriage 14 to move towards end 64of rack 12 in increments as bar 66 is moved up and down.

It is to be noted that the position of the lower end of lever arm 18causes the carriage to pull the lever arm as the carriage moves towardend 48 of rack 12. This is illustrated in FIG. 5 wherein a number offorces are shown in a schematic view of the jack and include thefollowing forces: force F represents the downward force due to theweight to be elevated; force F represents the force applied to lever arm18 by lever arm 16 at their common junction; force F represents theforce applied by lever arm 18 to rack 12 and carriage 14 due to thetendency for lever arm 18 to rotate about pin 52 under the influence offorce F force F represents the force applied by the jacking lever 36 tothe carriage as the bar 66 is moved downwardly; and force F representsthe force which must be applied manually to the bar 66 to cause force Fto be applied to the carriage. Upon observation of FIG. 5, it is clearthat force F; pulls the lower end of lever arm 18 forwardly and this isto be distinguished from the prior art structures which provide for apush to the lever arm inasmuch as the lower end of lever arm 18 has, inthe past structures, been pivotally coupled to the carriage in thevicinity denoted by the numeral 70 (FIGS. 2 and 5). In such a case, pin38 (where force F is applied) is below and to the rear of region 70 sothat a push in elfect is given to the lever arm to raise a weightthereon. By providing a pull instead of a push on lever arm 18, lessforce has been found to be required to move the carriage forwardly.

Since roller 62 engages the underside of rack 12, the rack absorbs someof the force applied by the lever arm in the vicinity of shaft 60. Thus,dog 32 is not driven against the teeth with an extremely large force aswould exist if all of the force exerted by lever arm 18 were to be takenup by the carriage. Thus, the teeth are relieved of any substantialpressure which would tend to cause them to burr and thereby to bedamaged. In the prior art structures, all of the force applied by thelever arm is taken up by the carriage and, as a result, the force on theteeth applied by the dog structure is extremely high and, unless theteeth are of high quality material, burring of the teeth takes place ina relatively short time and after relatively a few number of uses of thejack. Thus, the presence of roller 62 effectively relieves the pressureon the teeth and prolongs the life of the lifting jack of thisinvention.

The teachings of this invention can be applied to an existing bumperjack of the type normally provided as standard equipment on manyautomobiles today. To utilize a conventional bumper jack, only the rackand carriage of the same are utilized, the foot plate is not needed. Thefeet 30 are first welded or otherwise rigidly aflixed to the ends of therack and then projections 56 are secured to carriage 14 in any suitablemanner, such as by welding.

Thereafter, lever arms 16 and 18 are connected by pins 50 and 60 to rack12 and carriage 14 respectively, whereby the jack is complete and readyfor use. The lug wrench, which normally is utilized with the bumperjack, can be used with lifting jack 10. A slight modification may berequired on jacking lever 36 to cause its outer tubular end 68 to extendlongitudinally of the rack as shown in FIG. 2. This is for theconvenience of the user where the lifting jack is disposed beneath theunderside of a vehicle and jacking area is limited. If desired, a kitcan be prepared for commercial sales by assembling the necessarycomponents for transforming a conventional bumper jack into the liftingjack of this invention.

Lifting jack provides an extremely rugged structure which minimizes theforce required to elevate a given weight and also prolongs the life ofthe jack due to the fact that the teeth of the rack do not become burredover extended periods of use of the jack. The jack can be effectivelystored in the trunk of an automobile since it can collapse inasmuch ascarriage 14 can be disposed adjacent to end 64 of rack 12 with leverarms 16 and 18 effectively extending longitudinally of the rack.

While one embodiment of the present invention has been illustrated anddescribed, it is clear that other embodiments can be made withoutdeparting from the scope of the present invention.

It is claimed:

1. In a lifting jack of the type having a rack adapted to be disposed ina generally horizontal position: a carriage having a front end and arear end and adapted tobe coupled to said rack for forward and reversemovement along the same; an arm pivotally secured to said carriageadjacent to said rear end and extending forwardly and upwardly therefromwhen said carriage is mounted on said rack, said arm having weightsupporting means adjacent to the upper end thereof; and means secured tosaid arm for coupling the same to said rack at a location to cause saidweight-supporting means to be elevated as said carriage is movedforwardly along said rack.

2. In a lifting jack of the type having a rack adapted to be disposed ina generally horizontal position: a carriage having a front end, a rearend, and a bottom extremity and adapted to be coupled to said rack forforward and reverse movement along the same; an arm pivotally secured tosaid carriage adjacent to said rear end and said bottom extremity andextending forwardly and upwardly therefrom when said carriage is mountedon said rack, said arm having weight supporting means adjacent to theupper end thereof; means secured to said arm for coupling the same tosaid rack at a location to cause said weight-supporting means to beelevated as said carriage is moved forwardly along said rack; and meanscoupled to said arm for shiftably engaging the underside of the rack,whereby the rack will be in load-bearing relationship to the arm.

3. In a lifting jack as set forth in claim 2, wherein said engagingmeans includes a roller adapted to be disposed in rolling engagementwith the underside of the rack.

4. In a lifting jack as set forth in claim 2, wherein said arm comprisesa pair of spaced sections adapted to be disposed on opposed sides of therack, said engaging means being disposed between and coupled to said armsections and adapted to be disposed in rolling engagement with theunderside of the rack.

5. In a lifting jack: a rack adapted to be disposed in a horizontalposition; a carriage having a pair of opposed ends and being mounted onsaid rack for movement in opposite directions along the same; a firstarm having weight-supporting means at one end thereof; a second armpivotally secured to and extending upwardly from one extremity of saidrack, the upper end of said second arm being pivotally secured to saidfirst arm intermediate the ends of the latter, the opposite end of saidfirst arm being pivotally coupled to said carriage at the end thereofremote from said one extremity of the rack, whereby saidweight-supporting means will be raised and lowered as said carriagemoves toward and away from said one eX- tremity.

'6. In a lifting jack as set forth in claim 5, wherein is provided aprojection secured to and extending outwardly from said remote end ofthe carriage with said projection being disposed longitudinally of saidrack, said opposite end of the first arm being pivotally connected tosaid projection.

7. In a lifting jack as set forth in claim 5, wherein said rack isprovided with a bottom surface, said carriage having a projectionextending below said bottom surface of the rack, said opposite end ofthe first arm being connected to said projection, and wherein isincluded means coupled to said opposite end of the first arm andshiftably engaging said bottom surface for holding said opposite endagainst upward movement when a weight is supported by saidweight-supporting means.

8. In a lifting jack as set forth in claim 7, wherein said first armincludes a pair of sections on opposed sides of the rack, said holdingmeans including a roller between said sections with the roller normallyin engagement with said bottom surface.

9. In a lifting jack of the type having a rack adapted to be disposed ina horizontal position and a carriage mounted on and movable along saidrack in opposite directions: a first arm and a second arm; means on saidfirst arm for pivotally connecting one end thereof to one extremity ofsaid rack; means pivotally connecting the other end of the first arm tosaid second arm between the ends of the latter, said second arm havingweight-supporting means adjacent to one end thereof; and means on theopposite end of the second arm for pivotally coupling the same to saidcarriage adjacent to the end thereof remote from said one extremity ofsaid rack.

10. In a lifting jack as set forth in claim 9, wherein said couplingmeans includes a projection adapted to be rigidly secured to saidcarriage and to extend downwardly therefrom, said second arm beingpivotally mounted on said projection, and means extending laterally fromsaid projection for shiftable engaging the underside of the rack whensaid first and second arms are coupled to said rack and said carriagerespectively.

11. In a lifting jack as set forth in claim 9, wherein is provided meansadapted to be secured to the ends of the rack for supporting the same ina substantially horizontal position above a supporting surface.

12. In a lifting jack: a rack adapted to be disposed in a generallyhorizontal position and provided with a plurality of longitudinallyspaced teeth thereon; a carriage shiftably mounted on said rack andhaving an actuatable machanism engageable with the teeth for moving thecarriage in increments along the rack when the mechanism is actuated; anarm pivotally secured to said carriage adjacent to one end thereof andnormally extending upwardly therefrom and toward the opposite endthereof,

said arm having weight-supporting means thereon adjacent to the upperend thereof; and means coupling the arm to said rack to cause saidweight means to be elevated as said carriage moves along said rack withsaid opposite end of the carriage in advance of said one end thereof.

References Cited UNITED STATES PATENTS 1,121,417 12/1914 Tann 254-1081,545,380 7/1925 Woodings 254108 2,463,772 3/1949 Hunz 25411O 3,313,5224/1967 Ulm 254-108 3,334,866 8/1967 Bergamino 254-108 RICHARD C.RIORDON, Primary Examiner DAVID R. MELTON, Assistant Examiner

